1. Field of the Invention
The present invention relates to a cleaning device for contact lenses.
2. Description of the Related Art
In order to clean a contact lens, in general, the contact lens is taken off of a naked eye is held by the palm of a hand or the tip of finger, and is cleaned by dropping a cleaning liquid on its surface, followed by rubbing the contact lens with the tip of the finger. Dirt (particularly fat contained in tears) stained on the surface of a contact lens is thereby removed. After removal from the tip of the finger, the contact lens is rinsed with a rinsing liquid such as distilled water or the like. Thereafter, it is sterilized by boiling it in a preserving liquid such as a physiological saline solution or the like.
Recently, there has been developed a cleaning device for contact lenses which automatically performs a cleaning process, a rinsing process and a boiling process such as described above. The present inventors have found the conventional device to have the following problem. Namely, in the cleaning device for contact lenses of this kind, it is necessary to use the physiological saline solution at least in the rinsing process and the boil process. Furthermore, if the feeding tank of the physiological saline solution is disposed so as to miniaturize the device and to simplify the maintenance of the device, the physiological saline solution must be used in the cleaning process, too.
As mentioned above, in the cleaning device for contact lens of this kind, there are the following drawbacks. Since the consumption rate of the expensive physiological saline solution is large and the burden of the operation for feeding or discharging the physiological saline solution is large for the user, the cost for cleaning the contact lens is increased and the operation for cleaning the contact lens becomes troublesome. Furthermore, since the feeding tank or the discharging tank is enlarged, the device increases in size.
Accordingly, it is desirable to decrease the consumption rate of the physiological saline solution. Furthermore, it is also necessary to simplify and miniaturize the structure of the device, and to improve the durability and ease of maintenance.
Furthermore, it is desirable to use a liquid level sensor in order to automatically perform each process. By use of the liquid level sensor, it is possible to automatically feed a certain amount of the liquid. The conventional liquid level sensor, however, has the following drawbacks. First, of all, it is known to use an electrode-bar type of liquid level sensor in which plural conductive electrode-bars are mounted above the surface of a liquid and detect the fluid level via an electric communication between two electrode-bars. However, since it is necessary to install the electrode-bars onto a pivoting cover member which closes an opening portion of a cleaning chamber, it is necessary to rotate the electrode-bars when the cover member is pivoted and it is also necessary to run the insulated wires from the cover member to the housing. Furthermore, the electrode-bars make maintenance more difficult. On the other hand, in a capacitive type of liquid level sensor in which an electrode-bar formed on the housing is normally contacted with the liquid and which detects the surface of the liquid by a change of contact capacitance of the electrode-bar, it is possible to continuously detect a change of the surface of the liquid, but a circuit for processing the electric signal from the sensor is complicated and becomes expensive.